Lithium and its isotopic ratio ^{6}Li/^{7}Li in the atmospheres of some sharp-lined roAp stars
Abstract
The lines of lithium at λ 6708Å and λ 6103Å in high-resolution spectra of some sharp-lined rotating roAp stars are analyzed using the three spectral-synthesis codes STARSP, ZEEMAN2, and SYNTHM. The lines from the VALD database were supplemented by lines of rare-earth elements from the DREAM database and new lines calculated using the NIST energy levels. Our synthetic-spectrum calculations take into account magnetic splitting and other line-broadening effects. Lithium overabundances were found in the atmospheres of the stars based on our analysis of both λ 6103 and λ 6708 lithium lines, with high values of the ^{6}Li/^{7}Li isotope ratio (0.2div0.5). This can be explained if lithium is produced in spallation reactions and the surface ^{6}Li and ^{7}Li is preserved by the strong magnetic fields in the upper layers of the stellar atmospheres, around the poles of the dipole field.
- Publication:
-
Physics of Magnetic Stars
- Pub Date:
- 2007
- Bibcode:
- 2007pms..conf..341S